The invention relates to a drive unit for a hybrid motor vehicle which drive unit is disposed between an internal combustion engine and a transmission for transmitting power from the drive motor to the transmission.
DE 43 23 601 A1 discloses a drive unit for a hybrid motor vehicle which includes an input shaft, a single-disc dry clutch, an output shaft and a starter-generator structure. The input shaft is driven by the internal combustion engine. Within the drive unit, the input shaft is connected to the primary side of the clutch. The output shaft extends to the transmission. Within the drive unit, the output shaft is connected to the secondary side of the clutch and to the starter-generator. When the clutch is engaged or closed, a power transmission path is established from the internal combustion engine via the input shaft and the clutch to the output shaft. The shift state of the clutch is determined by a disengagement rod, a throw-out bearing and an engagement spring effective in an axial direction. During electric motor operation, the clutch is deactivated in order to disconnect the internal combustion engine from the motor-generator. To this end, the engagement spring is held by a disengagement rod in its open position that is, a relatively high force which is effective over a desired period must be provided via the disengagement rod and the throw-out bearing. No safety device is shown which, upon failure of an auxiliary power supply, keeps the clutch open during operation of the vehicle by the electric motor.
It is the object of the present invention to improve the operational safety of the drive unit.